For each department in the 'employees' table, concatenate the names of employees who have a salary greater than 50000, separated by a comma and ordered by their salaries in ascending order.
CREATE TABLE employees (id INTEGER, name VARCHAR, department VARCHAR, salary INTEGER); INSERT INTO employees (id, name, department, salary) VALUES (1, 'Alice', 'HR', 60000), (2, 'Bob', 'IT', 45000), (3, 'Charlie', 'IT', 70000), (4, 'David', 'HR', 55000);
```sql
SELECT 
    department,
    GROUP_CONCAT(name ORDER BY salary ASC SEPARATOR ', ') AS employees
FROM 
    employees
WHERE 
    salary > 50000
GROUP BY 
    department;
```
```sql
SELECT 
    department,
    GROUP_CONCAT(name ORDER BY salary ASC SEPARATOR ', ') AS employees
FROM 
    employees
WHERE 
    salary > 50000
GROUP BY 
    department;
```